The invention relates to a tanker loading assembly, comprising a first on-board hose arrangement with first coupling portion and a second submerged buoyant hose arrangement provided with second coupling portion for cooperation with the first coupling portion for obtaining a fluid-tight connection between the first and second hose arrangements.
Tanker-loading offshore, whereby a dynamically positioned tanker is employed, is a well establish practice. In general, such tankers are fitted out such that that they are able to arrive at a designated location at sea, position themselves in a stable mode, pick up the second coupling portion which is attached at one end of a tethered submerged buoyant hose arrangement, and connect this second coupling portion to the mating on-board first coupling portion.
Picking up the second coupling portion is often a process involving manual labour due to need to pick up messenger wires and to connect these to winches on the ship. Since the working on open decks of vessels, particularly in freezing or high wave conditions is dangerous, it is obvious that a fairly low operability is achieved in the more onerous seas such as the North Sea, for example.
The other end of the hose arrangement which is permanently attached to an oil or gas production facility, allows the oil or gas to flow into the tanker. During this operation the tanker maintains its position by appropriate means (e.g. its DP capability).
One such hose arrangement, to work in conjunction with a DP tanker, is described in U.S. Pat. No. 5,275,510 “Offshore Tanker Loading System”.
A complication occurs if such operation is to be performed in ice infested waters. Particularly if significant ice sheets and smaller and larger iceberg bits are present, the damage potential of the hose arrangement is very high if such hose arrangement is connected to the tanker at some over the side position. One logical solution would be to pull in the hose into a moonpool created inside the tanker hull boundaries where ice sheet cannot get. It has been observed in testing however that ice sheets, when they break up under the action of the vessel moving relative to the ice, also often slip under the bottom plate of the hull. Therefore any hose parts exiting downwardly from a moonpool through the tanker bottom, also risks being damaged by ice sheets.